AIRCRAFT PERFORMANCE

IMPORTANCE OF PERFORMANCE DATA
The performance or operational information section of the Airplane Flight Manual/Pilot's Operating Handbook (AFM/POH) contains the operating data for the airplane; that is, the data pertaining to takeoff, climb, range, endurance, descent, and landing. The use of this data in flying operations is mandatory for safe and efficient operation. Considerable knowledge and familiarity of the airplane can be gained through study of this material....view all

STRUCTURE OF THE ATMOSPHERE
The atmosphere is an envelope of air that surrounds the earth and rests upon its surface. It is as much a part of the earth as the seas or the land. However, air differs from land and water inasmuch as it is a mixture of gases. It has mass, weight, and indefinite shape....view all

ATMOSPHERIC PRESSURE
Though there are various kinds of pressure, pilots are mainly concerned with atmospheric pressure. It is one of the basic factors in weather changes, helps to lift the airplane, and actuates some of the important flight instruments in the airplane. These instruments are the altimeter, the airspeed indicator, the rate-of-climb indicator, and the manifold pressure gauge....view all

PRESSURE ALTITUDE
Pressure altitude is the height above a standard datum plane. The airplane altimeter is essentially a sensitive barometer calibrated to indicate altitude in the standard atmosphere. If the altimeter is set for 29.92 in. Hg Standard Datum Plane (SDP), the altitude indicated is the pressure altitude—the altitude in the standard atmosphere corresponding to the sensed pressure....view all

DENSITY ALTITUDE
The more appropriate term for correlating aerodynamic performance in the nonstandard atmosphere is density altitude— the altitude in the standard atmosphere corresponding to a particular value of air density....view all

EFFECTS OF PRESSURE ON DENSITY
Since air is a gas, it can be compressed or expanded. When air is compressed, a greater amount of air can occupy a given volume. Conversely, when pressure on a given volume of air is decreased, the air expands and occupies a greater space. That is, the original column of air at a lower pressure contains a smaller mass of air....view all

EFFECT OF TEMPERATURE ON DENSITY
Increasing the temperature of a substance decreases its density. Conversely, decreasing the temperature increases the density. Thus, the density of air varies inversely with temperature. This statement is true only at a constant pressure....view all

EFFECT OF HUMIDITY (MOISTURE) ON DENSITY
The preceding paragraphs have assumed that the air was perfectly dry. In reality, it is never completely dry....view all